A dip like that is hard to remove – you can’t EQ it, as then the off-axis response will have a peak in it. Using Edge, I came up with a baffle for the Neo3; this is a quick prototype:

Prototype Neo3PDR Baffle

The on-axis response is shown in purple in the curve below. It’s not flat but it’s easy to EQ – the EQed response shown in green. I haven’t measured the off-axis response yet – that will tell if having a baffle this shape is any improvement. At the least, the baffle lifts up the bottom end, making the tweeter strain less with a low crossover point.

New Neo3 PDR tweeter baffle measurements, on-axis, with and without EQ

Update April 16th 2012

Here is the off-axis measurement (with no EQ). In the frequency range from 3-10 kHz, the frontal lobe is wider than with the ideal dipole, but as you can see it still behaves like a dipole with a distinct null at 90 degrees. (And this is not intended to be a 100% precise measurement, the mic position was determined with a tape measure and eyeballing the angle of the baffle.)